Answer to Question #121452 in Chemistry for Maryjoy Ngagasy

Question

If 0.2F of electricity is passed through a solution of dilute sulphuric acid during electrolysis calculate the mass and volume of hydrogen gas.

Answer 1

Solution:

Electrolysis of dilute sulphuric acid:

At cathode: 2H⁺ + 2e− ⟶ H₂

​At anode: 4OH⁻ ⟶ 2H₂O + 2O₂ + 4e−

Overall reaction: 2H₂O ⟶ 2H₂ + O₂

​It takes a transfer of 2 electrons to form each hydrogen molecule (H₂) from 2 hydrogen ions (H⁺).

Faraday's second law of electrolysis states that, when the same quantity of electricity is passed through several electrolytes, the mass of the substances deposited are proportional to their respective chemical equivalent or equivalent weight.

By the 2nd Law of electrolysis when 0.2 F of electricity was passed in the solution 0.2 equivalent of Hydrogen will be evolved.

Volume of 1 equivalent of Hydrogen at STP = 11.2 L

Volume of H₂ = 0.2 × Volume of 1 equivalent of Hydrogen at STP

Volume of H₂ = 0.2 × 11.2 = 2.24 L

Mass of H₂ = 0.2 × Equivalent weight of H₂

Mass of H₂ = 0.2 × 1.008 = 0.2016 g = 0.2 g

Answer:

Volume of H₂ is 2.24 L

Mass of H₂ is 0.2 g